/*
 *
 * Copyright 1999-2018 Alibaba Group Holding Ltd.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */

package com.alibaba.nacos.core.notify;

import com.alibaba.nacos.common.utils.ConcurrentHashSet;
import com.alibaba.nacos.core.notify.listener.SmartSubscribe;
import com.alibaba.nacos.core.notify.listener.Subscribe;

import java.util.Set;

/**
 * Event publisher
 *
 * @author <a href="mailto:liaochuntao@live.com">liaochuntao</a>
 */
public interface EventPublisher {

	/**
	 * Multi-event listener collection list
	 */
	Set<SmartSubscribe> SMART_SUBSCRIBES = new ConcurrentHashSet<>();

	/**
	 * Initializes the event publisher
	 *
	 * @param type {@link Class<? extends Event>}
	 * @param bufferSize Message staging queue size
	 */
	void init(Class<? extends Event> type, int bufferSize);

	/**
	 * The number of currently staged events
	 *
	 * @return event size
	 */
	long currentEventSize();

	/**
	 * Add listener
	 *
	 * @param subscribe {@link Subscribe}
	 */
	void addSubscribe(Subscribe subscribe);

	/**
	 * Remove listener
	 *
	 * @param subscribe {@link Subscribe}
	 */
	void unSubscribe(Subscribe subscribe);

	/**
	 * publish event
	 *
	 * @param event {@link Event}
	 * @return publish event is success
	 */
	boolean publish(Event event);

	/**
	 * Notify listener
	 *
	 * @param subscribe {@link Subscribe}
	 * @param event {@link Event}
	 */
	void notifySubscriber(Subscribe subscribe, Event event);

	/**
	 * shutdown this publisher
	 */
	void shutdown();
}
